Using GIS on Ometepe
Challenges | Research Questions | Preliminary Analysis

Preliminary Analysis of GIS Data

This preliminary analysis discusses the results from four sites: N-RIO-2, 11, 12, and 23. (These sites were chosen as a representative sample, since it was not possible in the span of this class to digitize all 78 sites identified so far.) The sites present a diversity of elevation, from lake level (ca.26m AMSL) to 500m. Two sites (2 and 12) are located near water. Between them the sites have examples of every major type of motif found on Ometepe.

The sites were digitized onscreen in ArcView from hand-drawn field maps that had been scanned and then cleaned up. The UTM coordinates (Zone 16F, NAD 1927) of the site datums were derived from both field estimates and from GPS coordinates. Each site was digitized individually and then projected using Projector! and EdTools extensions. Selected fields relevant to the research questions were imported from the master project database to the shapefile attribute tables. The tables were then queried to derive the results you see below.

Sites: 2 | 11 | 12 | 23

Tabular Data


Rectilinear: 36%
Curvilinear: 36%
Zoomorphic: 0%
Anthropomorphic: 45%
Illegible: 18%

Curvi and Recti: 2 (50% correlation)
Curvi and Anthro: 0 (0% correlation)
Recti and Anthro: 0 (0% correlation)

Elevation: ca. 30m
Proximity to water: <10m


Rectilinear: 43%
Curvilinear: 57%
Zoomorphic: 14%
Anthropomorphic: 21%

Curvi and Recti: 5 (62.5%C, 87.5% R correl)
Curvi and Anthro: 1 (12.5% C, 33.3% A correl)
Recti and Anthro: 0 (0% correlation)
Zoo and others: 0 (0% correlation)

Elevation: ca. 210m
Proximity to water: 1300m to lake, 675m to watercourse


Rectilinear: 29%
Curvilinear: 71%
Zoomorphic: 19%
Anthropomorphic: 19%

Curvi and Recti: 4(27%C, 67% R correl)
Curvi and Anthro: 1 (7% C, 25% A correl)
Recti and Anthro: 0 (0% correlation)
Zoo and Anthro: 2 (50% correlation)

Elevation: ca. 190m
Proximity to water: 1450m to lake, 90m to watercourse


Rectilinear: 14% 4
Curvilinear: 93% 27
Zoomorphic: 3% 1
Anthropomorphic: 21% 6

Curvi and Recti: 3 (11%C, 75% R correl)
Curvi and Anthro: 2 (7% C, 33.3% A correl)
Recti and Anthro: 0 (0% correlation)
Zoo and Anthro: 0 (0% correlation)

Elevation: ca. 90m
Proximity to water: 500m to lake, 50m to watercourse

Preliminary Answers to research questions

What motifs occur at higher or lower elevations?
The data above suggest that anthropomorphic motifs are more common at lower elevations, while zoomorphic motifs are more common higher. Curvilinears are a larger proportion of all motifs and of abstract motifs at higher elevations.

What types of motif are located close to water?
Anthropomorphic motifs seem to be most closely associated with the lake. Motif proportions do not seem to vary with proximity to streams.

Do representative motifs occur most often with curvi- or rectilinear forms?
Only anthropomorphic motifs appear with curvilinear forms. About 25-33% of A motifs occur with C.

Do curvilinear motifs and rectilinear motifs occur together, or are they typically clustered separately?
Correlations between C and R motifs are much higher than any other type. A majority of curvilinear motifs appear on the same boulder as curvilinear ones.


The sample of four sites discussed above, if it is representative, suggests some tentative conclusions.